Frequency generators are broadly utilized in the field of digital engineering, particularly as clock generators. However, numerous applications not only require fixed frequencies such as those generated, e.g., by quartz oscillators, but also digitally adjustable frequencies. Certain applications also require very high frequencies that should be created exclusively on a chip and not externally supplied due to power dissipation and EMC.
According to the state of the art, the PLLs (Phase Locked Loops) utilized for this purpose contain an oscillator in the form of a VCO (Voltage Controlled Oscillator). The disadvantage of these oscillators is that the control voltage that defines the frequency needs to be very precise and free of interferences because any interference voltage on the control voltage leads to frequency changes and consequently to a jitter in the generated frequency.